递归地打印链表

public class PrintListByRecursive {

    public static void printList(ListNode head) {
        if(head == null){
            return;
        }
        System.out.println(head.val);
        printList(head.next);
    }

    public static void main(String[] args) {
        ListNode head = new ListNode(1);
        ListNode node1 = new ListNode(2);
        ListNode node2 = new ListNode(3);
        ListNode node3 = new ListNode(4);
        ListNode node4 = new ListNode(5);
        head.next = node1;
        node1.next = node2;
        node2.next = node3;
        node3.next = node4;
        printList(head);
    }
}

public class ListNode {
    int val;
    ListNode next;
    ListNode(int x) { val = x; }
}